Lidocaine, a local anesthetic, decreases the turnover rate of acetylcholine in cortex but not in striatum, hippocampus or diencephalon when administered in subconvulsive doses. Another local anesthetic, cocaine, increases the turnover rate of acetylcholine in cortex and diencephalon but not in striatum or hippocampus. These results suggest that the increase of acetylcholine turnover rate induced by cocaine may be unrelated to the local anesthetic effect and may be due to its CNS stimulant action. Deprivation of REM sleep does not alter the turnover rate of acetylcholine in cortex, striatum, hippocampus or diencephalon.